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Author: Alexander Dean Todd Publisher: ISBN: Category : Languages : en Pages : 292
Book Description
While much of the recent work regarding carbon materials has centered on monolayer graphene, we have focused on the relatively inexpensive, and readily accessible graphite oxide (GO) and thermally-reduced graphite oxide (TRG) to develop new catalysts and polymer composites. Indeed, the reactivity and physical properties inherent to GO has led to improved GO-based catalysis and composite materials with more robust mechanical properties. GO in combination with zeolite NaY dehydrated a variety of alcohols to their corresponding olefinic products under mild conditions. Although GO at 15 wt% loading was an active dehydration catalyst, it was found that the GO loading could be reduced by 50% when used cooperatively with NaY (7.5 wt%). Ultimately, it was determined that the acidity of GO was able to convert the NaY into an acidic form without the added step of ammonium exchange or high-temperature calcination. For the former application, polyethylene/thermally reduced graphite oxide (TRG) composites have been synthesized under mild conditions (1 atm ethylene and 40 °C) using (n-BuCp)2ZrCl2 activated with methylaluminoxane (MAO) as the polymerization catalyst. Although the thermal properties of the aforementioned composites were relatively unchanged when compared to polyethylene, significant enhancements in the mechanical properties were observed (e.g., up to 57% increase in the tensile strength and 170% increase the Young’s modulus for composites containing 5.2 wt% TRG). Donor-acceptor conjugated polymers, where the backbone consists of an alternating electron rich and electron poor [pi]-conjugated repeat unit, have some of the highest reported power conversion efficiencies to date. Conventional synthetic methods for synthesizing donor-acceptor conjugated polymers have relied upon Pd-catalyzed Stille- or Suzuki-type polycondensations and typically afford ill-defined polymers with variable molecular weights and broad polydispersities (Đs). We were interested in synthesizing well-defined donor-acceptor conjugated polymers and have developed a method to polymerize a donor-acceptor monomer based on thiophene and 5,6-difluorobenzotriazole in a controlled fashion using Ni-catalyzed Kumada catalyst-transfer polycondensation (KCTP). By altering the initial catalyst-to-monomer ratio, the M [subscript n] of the resulting polymers (PFBTzHT) ranged from 6.2 kDa – 22.9 kDa, while maintaining narrow Đs (≤ 1.4). Moreover, under the optimized polymerization conditions, the M [subscript n] was found to increase linearly with monomer conversion. Ultimately, the quasi-living nature of the polymerization allowed for the synthesis of well-defined diblock copolymers of PFBTzHT and poly(3-hexylthiophene) (PFTBTz-b-P3HT).
Author: Alexander Dean Todd Publisher: ISBN: Category : Languages : en Pages : 292
Book Description
While much of the recent work regarding carbon materials has centered on monolayer graphene, we have focused on the relatively inexpensive, and readily accessible graphite oxide (GO) and thermally-reduced graphite oxide (TRG) to develop new catalysts and polymer composites. Indeed, the reactivity and physical properties inherent to GO has led to improved GO-based catalysis and composite materials with more robust mechanical properties. GO in combination with zeolite NaY dehydrated a variety of alcohols to their corresponding olefinic products under mild conditions. Although GO at 15 wt% loading was an active dehydration catalyst, it was found that the GO loading could be reduced by 50% when used cooperatively with NaY (7.5 wt%). Ultimately, it was determined that the acidity of GO was able to convert the NaY into an acidic form without the added step of ammonium exchange or high-temperature calcination. For the former application, polyethylene/thermally reduced graphite oxide (TRG) composites have been synthesized under mild conditions (1 atm ethylene and 40 °C) using (n-BuCp)2ZrCl2 activated with methylaluminoxane (MAO) as the polymerization catalyst. Although the thermal properties of the aforementioned composites were relatively unchanged when compared to polyethylene, significant enhancements in the mechanical properties were observed (e.g., up to 57% increase in the tensile strength and 170% increase the Young’s modulus for composites containing 5.2 wt% TRG). Donor-acceptor conjugated polymers, where the backbone consists of an alternating electron rich and electron poor [pi]-conjugated repeat unit, have some of the highest reported power conversion efficiencies to date. Conventional synthetic methods for synthesizing donor-acceptor conjugated polymers have relied upon Pd-catalyzed Stille- or Suzuki-type polycondensations and typically afford ill-defined polymers with variable molecular weights and broad polydispersities (Đs). We were interested in synthesizing well-defined donor-acceptor conjugated polymers and have developed a method to polymerize a donor-acceptor monomer based on thiophene and 5,6-difluorobenzotriazole in a controlled fashion using Ni-catalyzed Kumada catalyst-transfer polycondensation (KCTP). By altering the initial catalyst-to-monomer ratio, the M [subscript n] of the resulting polymers (PFBTzHT) ranged from 6.2 kDa – 22.9 kDa, while maintaining narrow Đs (≤ 1.4). Moreover, under the optimized polymerization conditions, the M [subscript n] was found to increase linearly with monomer conversion. Ultimately, the quasi-living nature of the polymerization allowed for the synthesis of well-defined diblock copolymers of PFBTzHT and poly(3-hexylthiophene) (PFTBTz-b-P3HT).
Author: Sajjad Haider Publisher: Elsevier ISBN: 0323852963 Category : Technology & Engineering Languages : en Pages : 516
Book Description
Renewable Polymers and Polymer-Metal Oxide Composites: Synthesis, Properties, and Applications serves as a reference on the key concepts of the advances of polymer-oxide composites. The book reviews knowledge on polymer-composite theory, properties, structure, synthesis, and their characterization and applications. There is an emphasis on coupling metal oxides with polymers from renewable sources. Also, the latest advances in the relationship between the microstructure of the composites and the resulting improvement of the material’s properties and performance are covered. The applications addressed include desalination, tissue engineering, energy storage, hybrid energy systems, food, and agriculture. This book is suitable for early-career researchers in academia and R&D in industry who are working in the disciplines of materials science, engineering, chemistry and physics. Provides basic principles, theory and synthetic methods of composite materials, polymer composites and metal oxides Reviews the latest advances in polymer-oxide-based applications in medicine, water treatment, energy and sensing Discusses materials from renewable resources, including lifecycle assessment, economic aspects and potential application in tissue engineering, photovoltaics and food packaging
Author: Mostafizur Rahaman Publisher: Woodhead Publishing ISBN: 0128216409 Category : Technology & Engineering Languages : en Pages : 817
Book Description
Polymer Nanocomposites Containing Graphene: Preparation, Properties and Applications provides detailed up-to-date information on the characterization, synthesis, processing, properties and application of these materials. Key topics that are covered in the book include: the methods of synthesis and preparation of graphene as well as different processes and methods of functionalization and modification of graphene for improving composite properties. The preparation techniques focus on which method is advantageous for getting improvements in properties along with their drawbacks. The structure and property relationships are also discussed in detail. The issues related to graphene dispersion in polymer matrices is also addressed as well as the use of graphene as reinforcement in thermoset resins. The different properties of the composites like mechanical, electrical, dielectric, thermal, rheological, morphology, spectroscopy, electronic, optical, and toxicity are reviewed from the geometrical and functional point of view. Applications cover electrical and electronic fields, flame and fire retardancy, structural, sensing and catalysis, membrane, in fuel cell and solar energy, hydrogen production, aerospace engineering, packaging, and biomedical/bioengineering fields. Up-to-date patents on graphene-polymer nanocomposites are also covered. Those working in graphene-based materials will benefit from the detailed knowledge presented in this book on graphene synthesis, composite preparation methods, and the related problems associated with them. The book will enable researchers to select the appropriate composite as per their respective field of application. Presents novel approaches for the preparation of graphene, its modification and nanocomposites with enhanced properties for state-of-the-art applications Special attention is given to how graphene is synthesized through different routes, their functionality, dispersion related matters and structural aspects controlling the composite properties for various applications All synthesis methodology and functionalization procedure for graphene is discussed
Author: Arun Kumar Nandi Publisher: Royal Society of Chemistry ISBN: 1788019687 Category : Science Languages : en Pages : 457
Book Description
There is an immense variety of research on polymer functionalized graphene (PFG). Functionalization of graphene is necessary for improvement of the compatibility with polymers. Applications of these graphene polymer hybrids include in chemical and biological sensing, photovoltaic devices, supercapacitors and batteries, dielectric materials and drug/gene delivery vehicles. This book will shed light on the synthesis, properties and applications of these new materials, covering two methods (covalent and noncovalent) for producing polymer functionalized graphene. Chapters cover physical, optical, mechanical and electronic properties, applications of polymer functionalized graphene in energy harvesting and storage, and uses in biomedicine and bioengineering. Written by an expert in the field, Polymer Functionalized Graphene will be of interest to graduate students and researchers in polymer chemistry and nanoscience.
Author: Mohammad Jawaid Publisher: Springer Nature ISBN: 9811917507 Category : Technology & Engineering Languages : en Pages : 425
Book Description
This book provides an overview of the fundamentals and recent advances in the field of carbon composite catalysts, including graphene, carbon nanotubes, mesoporous carbons, graphitic carbon nitrides, and related composites. Special focus is placed on their controllable preparation and applications in the gas phase, liquid phase, electrochemical, and photocatalytic reactions, as well as defect and surface chemistry-related catalytic activities of carbon materials. Some perspectives are highlighted on the development of more efficient carbonaceous catalysts featuring high stability, low cost, optimized structures, and enhanced performance, which are the key factors to accelerate the designed preparation and commercialization of carbon composite catalysts. The book will also present the latest studies of carbon-based composite catalysts for clean energy change and storage, nature protection, and essential industrial production and storage and include the key challenges and future opportunities in this exciting field.
Author: Liwen Xing Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Donor-acceptor (D-A) conjugated polymers, as one type of organic semiconducting materials, have drawn lots of attention for the application in organic electronics due to their lowered band gaps and high charge mobility. The polymerization based on cross dehydrogenative coupling (CDC) is an atom-economic synthetic method for D-A polymers as it significantly simplifies the overall synthetic routes by applying C-H bond activation during the polymerization. Two different dual catalytic systems – Au/Ag and Pd/Ag for CDC polymerizations were investigated here. Despite both transformations occurring by a similar mechanistic sequence, dramatically different kinetic behaviors and polymerization results were discovered. The Pd/Ag system produced unexpectedly low homocoupling defects and high molecular weight polymers despite the small molecule coupling reaction proceeding inefficiently. Conversely, Au/Ag system produced low molecular weight polymers with lots of homocoupling defects while catalyzing an efficient small molecule coupling reaction. While the findings in this work provide valuable insight for future studies in obtaining high-molecular weight D-A polymers via CDC, these findings could affect the design of substrates in late-stage C−H functionalization.
Author: Lauren Kang Publisher: ISBN: Category : Languages : en Pages : 69
Book Description
[pi]-Conjugated polymers are materials of interest for use in organic electronics. Within these polymers, donor-acceptor polymers are favorable for solar cell applications due to improved charge mobility, better absorption in the low energy region of the solar spectrum, and tunable band gaps. One of the barriers to commercializing these donor-acceptor materials is that their synthetic pathways are complex because of the alternating repeat units in the polymer. To address this, the applications of cross dehydrogenative coupling (also called oxidative CH/CH cross-coupling) toward the synthesis of donor-acceptor polymers was explored. In this work, the roles of specific reagents in a one-pot gold- and silver-catalyzed cross dehydrogenative coupling and the factors that contribute to selectivity for cross-coupling rather than homo-coupling are elucidated. Based on our results, we conclude that the difference in rate of C-H activation by gold and silver dominate the percentage of alternating repeat units in the final polymer, which may be exploited to control the ratio of electron-rich to electron-poor monomers.
Author: Sanjay Mavinkere Rangappa Publisher: Woodhead Publishing ISBN: 0128237902 Category : Technology & Engineering Languages : en Pages : 642
Book Description
Innovations in Graphene-Based Polymer Composites reviews recent developments in this important field of research. The book's chapters focus on processing methods, functionalization, mechanical, electrical and thermal properties, applications and life cycle assessment. Leading researchers from industry, academia and government research institutions from across the globe have contributed to the book, making it a valuable reference resource for materials scientists, academic researchers and industrial engineers working on recent developments in the area of graphene-based materials, graphene-based polymer blends and composites. Readers will gain insights into what has been explored to-date, along with associated benefits and challenges for the future. Presents a strong emphasis on synthesis methods, functionalization, processing and properties Includes chapters on characterization, electrical conductivity and modeling and simulation Provides recent advances in applications, including drawbacks and future scope
Author: Andrew Dove Publisher: Royal Society of Chemistry ISBN: 1788016793 Category : Technology & Engineering Languages : en Pages : 668
Book Description
In recent years polymerisation using organocatalysts has become an appealing alternative to more traditional metal-based catalysts. Conferring numerous advantages including low cost and ease of use, as well as the ability to precisely control the synthesis of advanced polymer structures, organocatalysts are increasingly used in polymer synthesis. Organic Catalysis for Polymerisation provides a holistic overview of the field, covering all process in the polymer synthesis pathway that are catalysed by organic catalysts. Sub-divided into two key sections for ease of use, the first focuses on recent developments in catalysis and the applications of catalysts to the full range of polymerisations that they have been utilised in; the second concerning monomers, arranges the field by monomer type and polymerisation mechanism. The book will therefore, provide a complimentary view of the field, providing both an overview of state-of-the-art catalyst development and also the best methodologies available to create specific polymer types. Edited by leading figures in the field and featuring contributions from researchers across the globe, this title will serve as an excellent reference for postgraduate students and researchers in both academia and industry interested in polymer chemistry, organic chemistry, catalysis and materials science.
Author: Ray Hoff Publisher: John Wiley & Sons ISBN: 0470504420 Category : Technology & Engineering Languages : en Pages : 599
Book Description
A one-stop resource for understanding and applying polymerization catalysts An edited volume featuring contributions from leading researchers, the Handbook of Transition Metal Polymerization Catalysts covers the design and synthesis of catalysts, and their applications in synthesis of polymers. Dealing with those polymerization catalysts that afford commercially acceptable yields of polymer with respect to catalyst mass and promising newer catalysts, this practical reference provides polymer and organic chemists with a comprehensive overview of the known methods for developing and applying these important catalysts. With both recent advances and historically important catalysts, the subjects covered in this text include: Metal alkyls and other compounds that function as co-catalysts with a large number of catalysts The varieties of porous silica either necessary or valuable in certain catalyst formulations Catalyst scale-up and commercialization Copper catalysts for olefin polymerization Morphology control Along with the above topics, the Handbook of Transition Metal Polymerization Catalysts provides tables of valuable data to assist in reproducing a synthesis or applying the knowledge to a new problem. Polymerization reactivities, polymer properties, monomer and solvent purity requirements, molecular weights, distribution, and reactivity ratios are also covered. The Handbook of Transition Metal Polymerization Catalysts offers an excellent one-stop resource for understanding and applying polymerization catalysts.
Author: Alexander Dean Todd
Author: Alexander Dean Todd
Author: Sajjad Haider
Author: Mostafizur Rahaman
Author: Arun Kumar Nandi
Author: Mohammad Jawaid
Author: Liwen Xing
Author: Lauren Kang
Author: Sanjay Mavinkere Rangappa
Author: Andrew Dove
Author: Ray Hoff